Aminocarbazole compounds as antibacterial agents

ABSTRACT

The aminocarbazole compounds are antibacterial agents. The emergence of drug-resistant bacteria calls for constant development of new antibacterial agents with the aim of generating medicaments that are potent against drug sensitive and resistant bacteria and are well tolerated. The present compounds are not only new, but have very valuable antimicrobial properties. These compounds showed a broad spectrum of activity against gram-positive and gram-negative bacteria, as well tuberculosis mycobacteria. They also showed potent activity against drug-resistant bacteria, such as MRSA and VRSA. The molecular target of these compounds was identified as DNA Gyrase B. Based on their pharmacological profiles, the present compounds may find important clinical applications for severe infectious diseases and tuberculosis.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 18/119,742, filed Mar. 9, 2023, now pending.

BACKGROUND 1. Field

The disclosure of the present patent application relates toaminocarbazole compounds, and particularly to 1-aminocarbazole compoundsas antibacterial agents.

2. Description of the Related Art

Infectious diseases caused by bacterial resistance to antibioticsconstitute an increasing threat to humans on a global scale. Anincreasing number of infectious bacteria, including tuberculosis,pneumonia, salmonellosis, and gonorrhea, are becoming progressivelychallenging to cure owing to the ineffectiveness of currently usedclinical antibiotics and present a serious health threat worldwide inthe medical community. The major concern of this global health threat isthe ability of microorganisms to develop one or several mechanisms ofresistance to antibiotics, rendering them inefficient for therapeutictreatment. The quest for discovering novel scaffolds with antimicrobialproperties is particularly challenging in hospital and healthcaresettings.

Similarly, the emergence of drug resistant bacteria calls for constantdevelopment of new antibacterial agents with the aim of generatingmedicaments that are potent against drug sensitive and resistantbacteria and are well tolerated.

Tuberculosis (TB) is one of the top 10 leading causes of mortalityworldwide and is the leading cause of death from infectious diseaseamong adults. It is a communicable disease caused by the bacteriumMycobacterium tuberculosis (MTB) that primarily affects the lungs,resulting in pulmonary TB. TB can also infect other sites of the body,causing extrapulmonary TB.

To date, no major changes in the treatment of TB have been made, and thecurrent standard treatment still involves a combination of fourantibiotics (isoniazid, rifampin, pyrazinamide, and ethambutol) givenfor two months followed by isoniazid and rifampicin for an additionalfour months. This anti-TB regimen has been successful in the treatmentof MTB H37Rv. However, the emergence of multidrug-resistant TB (MDR-TB)and extensively drug-resistant TB (XDR-TB), as well as HIV/TBco-infection cases, have made TB control more difficult. Moreover,treating resistant TB can take up to 24 months and might be associatedwith side effects and a low chance of cure. This, in turn, can lead topoor patient compliance, which can also contribute to the development ofresistance.

Despite the efforts to discover new anti-TB compounds, current therapiesare still facing the development of resistance and poor compliance dueto long treatment duration. Therefore, it is evident that there is anurgent need for the development of new potential antimicrobial compoundsgenerally, and anti-TB compounds specifically, that can act on newmolecular targets to overcome drug-resistant MTB strains and to controlthe wide spread of TB.

Thus, new compounds as antibacterial agents solving the aforementionedproblems are desired.

SUMMARY

The aminocarbazole compounds as antibacterial agents, in one embodiment,relates to a compound having the formula I:

or a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof, wherein: R₁ is hydrogen, C₁-C₆ alkyl, or C₃-C₆ cycloalkyl; R₂is hydrogen or a halogen; and R₃ is an aryl, heteroaryl, arylamine, orheteroarylamine, each of which may be optionally substituted with fromone to three substituents.

In another embodiment, the present subject matter relates to amethylamino carbazole compound having the formula I:

or a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof, wherein R₁ is methyl; R₂ is hydrogen or fluorine; and R₃ is aphenyl, a pyrimidine, a pyridine, an amino phenyl, an amino pyrimidine,or an amino pyridine, each of which phenyl, pyrimidine, and pyridine maybe optionally substituted with from one to three substituentsindependently selected from the group consisting of hydrogen, —COOH,—CH₂COOH, a trihaloalkoxy group, a trihaloalkyl group, and an alkoxygroup.

In a further embodiment, the present subject matter relates to acompound selected from the group consisting of2-(3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)phenyl)acetic acid (1);3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)benzoic acid (2);3-fluoro-N-methyl-6-(3-(trifluoromethoxy)phenyl)-9H-carbazol-1-amine(3); 3-fluoro-N-methyl-6-(3-(trifluoromethyl)phenyl)-9H-carbazol-1-amine(4); 3-fluoro-N-methyl-6-(pyrimidin-5-yl)-9H-carbazol-1-amine (5);3-((6-fluoro-8-(methylamino)-9H-carbazol-3-yl)amino)benzoic acid (6);3-fluoro-N1-methyl-N6-(3-(trifluoromethoxy)phenyl)-9H-carbazole-1,6-diamine(7);3-fluoro-N1-methyl-N6-(3-(trifluoromethyl)phenyl)-9H-carbazole-1,6-diamine(8); 3-fluoro-N6-(3-methoxyphenyl)-N1-methyl-9H-carbazole-1,6-diamine(9); 3-fluoro-N1-methyl-N6-(pyridin-3-yl)-9H-carbazole-1,6-diamine (10);and a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof.

Further contemplated herein are pharmaceutical compositions containingthese compounds, as well as methods of treating various bacterialinfections by administering the present compounds to a patient in needthereof.

These and other features of the present subject matter will becomereadily apparent upon further review of the following specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following definitions are provided for the purpose of understandingthe present subject matter and for construing the appended patentclaims.

Throughout the application, where compositions are described as having,including, or comprising specific components, or where processes aredescribed as having, including, or comprising specific process steps, itis contemplated that compositions of the present teachings can alsoconsist essentially of, or consist of, the recited components, and thatthe processes of the present teachings can also consist essentially of,or consist of, the recited process steps.

It is noted that, as used in this specification and the appended claims,the singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

In the application, where an element or component is said to be includedin and/or selected from a list of recited elements or components, itshould be understood that the element or component can be any one of therecited elements or components, or the element or component can beselected from a group consisting of two or more of the recited elementsor components. Further, it should be understood that elements and/orfeatures of a composition or a method described herein can be combinedin a variety of ways without departing from the spirit and scope of thepresent teachings, whether explicit or implicit herein.

The use of the terms “include,” “includes”, “including,” “have,” “has,”or “having” should be generally understood as open-ended andnon-limiting unless specifically stated otherwise.

The use of the singular herein includes the plural (and vice versa)unless specifically stated otherwise. In addition, where the use of theterm “about” is before a quantitative value, the present teachings alsoinclude the specific quantitative value itself, unless specificallystated otherwise. As used herein, the term “about” refers to a ±10%variation from the nominal value unless otherwise indicated or inferred.

As used herein, “halo” or “halogen” refers to fluoro, chloro, bromo, andiodo.

As used herein, “alkyl” refers to a straight-chain or branched saturatedhydrocarbon group. Examples of alkyl groups include methyl (Me), ethyl(Et), propyl (e.g., n-propyl and z′-propyl), butyl (e.g., n-butyl,z′-butyl, sec-butyl, tert-butyl), pentyl groups (e.g., n-pentyl,z′-pentyl, -pentyl), hexyl groups, and the like. In various embodiments,an alkyl group can have 1 to 40 carbon atoms (i.e., C₁-C₄₀ alkyl group),for example, 1-30 carbon atoms (i.e., C₁-C₃₀ alkyl group). In someembodiments, an alkyl group can have 1 to 6 carbon atoms, and can bereferred to as a “lower alkyl group” or a “C₁-C₆ alkyl group”. Examplesof lower alkyl groups include methyl, ethyl, propyl (e.g., n-propyl andz′-propyl), and butyl groups (e.g., n-butyl, z′-butyl, sec-butyl,tert-butyl). In some embodiments, alkyl groups can be substituted asdescribed herein. An alkyl group is generally not substituted withanother alkyl group, an alkenyl group, or an alkynyl group.

As used herein, “alkenyl” refers to a straight-chain or branched alkylgroup having one or more carbon-carbon double bonds. Examples of alkenylgroups include ethenyl, propenyl, butenyl, pentenyl, hexenyl,butadienyl, pentadienyl, hexadienyl groups, and the like. The one ormore carbon-carbon double bonds can be internal (such as in 2-butene) orterminal (such as in 1-butene). In various embodiments, an alkenyl groupcan have 2 to 40 carbon atoms (i.e., C₂-C₄₀ alkenyl group), for example,2 to 20 carbon atoms (i.e., C₂-C₂₀ alkenyl group) or 2 to 6 carbon atoms(i.e., C₂-C₆ alkenyl group). In some embodiments, alkenyl groups can besubstituted as described herein. An alkenyl group is generally notsubstituted with another alkenyl group, an alkyl group, or an alkynylgroup.

The term “substituted alkyl” as used herein refers to an alkyl group inwhich 1 or more (up to about 5, for example about 3) hydrogen atoms isreplaced by a substituent independently selected from the group: —O, —S,acyl, acyloxy, optionally substituted alkoxy, optionally substitutedamino (wherein the amino group may be a cyclic amine), azido, carboxyl,(optionally substituted alkoxy)carbonyl, amido, cyano, optionallysubstituted cycloalkyl, optionally substituted cycloalkenyl, halogen,hydroxyl, nitro, sulfamoyl, sulfanyl, sulfinyl, sulfonyl, and sulfonicacid. Some of the optional substituents for alkyl are hydroxy, halogenexemplified by chloro and bromo, acyl exemplified by methylcarbonyl;alkoxy, and heterocyclyl exemplified by morpholino and piperidino. Otheralkyl substituents as described herein may further be contemplated.

The term “substituted alkenyl” refers to an alkenyl group in which 1 ormore (up to about 5, for example about 3) hydrogen atoms is replaced bya substituent independently selected from those listed above withrespect to a substituted alkyl. Other alkenyl substituents as describedherein may further be contemplated.

As used herein, “heteroatom” refers to an atom of any element other thancarbon or hydrogen and includes, for example, nitrogen, oxygen, silicon,sulfur, phosphorus, and selenium.

As used herein, “aryl” refers to an aromatic monocyclic hydrocarbon ringsystem or a polycyclic ring system in which two or more aromatichydrocarbon rings are fused (i.e., having a bond in common with)together or at least one aromatic monocyclic hydrocarbon ring is fusedto one or more cycloalkyl and/or cycloheteroalkyl rings. An aryl groupcan have 6 to 24 carbon atoms in its ring system (e.g., C6-24 arylgroup), which can include multiple fused rings. In some embodiments, apolycyclic aryl group can have 8 to 24 carbon atoms. Any suitable ringposition of the aryl group can be covalently linked to the definedchemical structure. Examples of aryl groups having only aromaticcarbocyclic ring(s) include phenyl, 1-naphthyl (bicyclic), 2-naphthyl(bicyclic), anthracenyl (tricyclic), phenanthrenyl (tricyclic),pentacenyl (pentacyclic), and like groups. Examples of polycyclic ringsystems in which at least one aromatic carbocyclic ring is fused to oneor more cycloalkyl and/or cycloheteroalkyl rings include, among others,benzo derivatives of cyclopentane (i.e., an indanyl group, which is a5,6-bicyclic cycloalkyl/aromatic ring system), cyclohexane (i.e., atetrahydronaphthyl group, which is a 6,6-bicyclic cycloalkyl/aromaticring system), imidazoline (i.e., a benzimidazolinyl group, which is a5,6-bicyclic cycloheteroalkyl/aromatic ring system), and pyran (i.e., achromenyl group, which is a 6,6-bicyclic cycloheteroalkyl/aromatic ringsystem). Other examples of aryl groups include benzodioxanyl,benzodioxolyl, chromanyl, indolinyl groups, and the like. In someembodiments, aryl groups can be substituted as described herein. In someembodiments, an aryl group can have one or more halogen substituents,and can be referred to as a “haloaryl” group. Perhaloaryl groups, i.e.,aryl groups where all of the hydrogen atoms are replaced with halogenatoms (e.g., —C₆F₅), are included within the definition of “haloaryl”.In certain embodiments, an aryl group is substituted with another arylgroup and can be referred to as a biaryl group. Each of the aryl groupsin the biaryl group can be substituted as disclosed herein.

As used herein, “heteroaryl” refers to an aromatic monocyclic ringsystem containing at least one ring heteroatom selected from oxygen (O),nitrogen (N), sulfur (S), silicon (Si), and selenium (Se) or apolycyclic ring system where at least one of the rings present in thering system is aromatic and contains at least one ring heteroatom.Polycyclic heteroaryl groups include those having two or more heteroarylrings fused together, as well as those having at least one monocyclicheteroaryl ring fused to one or more aromatic carbocyclic rings,non-aromatic carbocyclic rings, and/or non-aromatic cycloheteroalkylrings. A heteroaryl group, as a whole, can have, for example, 5 to 24ring atoms and contain 1-5 ring heteroatoms (i.e., 5-20 memberedheteroaryl group). The heteroaryl group can be attached to the definedchemical structure at any heteroatom or carbon atom that results in astable structure. Generally, heteroaryl rings do not contain O—O, S—S,or S—O bonds. However, one or more N or S atoms in a heteroaryl groupcan be oxidized (e.g., pyridine N-oxide thiophene S-oxide, thiopheneS,S-dioxide). Examples of heteroaryl groups include, for example, the 5-or 6-membered monocyclic and 5-6 bicyclic ring systems shown below:where T is O, S, NH, N-alkyl, N-aryl, N-(arylalkyl) (e.g., N-benzyl),SiH₂, SiH(alkyl), Si(alkyl)₂, SiH(arylalkyl), Si(arylalkyl)₂, orSi(alkyl)(arylalkyl). Examples of such heteroaryl rings includepyrrolyl, furyl, thienyl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl,triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl,thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl,benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl,quinoxalyl, quinazolyl, benzotriazolyl, benzimidazolyl, benzothiazolyl,benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl,cinnolinyl, 1H-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl,naphthyridinyl, phthalazinyl, pteridinyl, purinyl, oxazolopyridinyl,thiazolopyridinyl, imidazopyridinyl, furopyridinyl, thienopyridinyl,pyridopyrimidinyl, pyridopyrazinyl, pyridopyridazinyl, thienothiazolyl,thienoxazolyl, thienoimidazolyl groups, and the like. Further examplesof heteroaryl groups include 4,5,6,7-tetrahydroindolyl,tetrahydroquinolinyl, benzothienopyridinyl, benzofuropyridinyl groups,and the like. In some embodiments, heteroaryl groups can be substitutedas described herein.

The term “optional” or “optionally” means that the subsequentlydescribed event or circumstance may or may not occur, and that thedescription includes instances where said event or circumstance occursand instances in which it does not. For example, “optionally substitutedalkyl” means either “alkyl” or “substituted alkyl,” as defined herein.

It will be understood by those skilled in the art with respect to anychemical group containing one or more substituents that such groups arenot intended to introduce any substitution or substitution patterns thatare sterically impractical and/or physically non-feasible.

The term “isomers” or “stereoisomers” as used herein relates tocompounds that have identical molecular formulae but that differ in thearrangement of their atoms in space. Stereoisomers that are not mirrorimages of one another are termed “diastereoisomers” and stereoisomersthat are non-superimposable mirror images are termed “enantiomers,” orsometimes optical isomers. A carbon atom bonded to four non-identicalsubstituents is termed a “chiral center.” Certain compounds herein haveone or more chiral centers and therefore may exist as either individualstereoisomers or as a mixture of stereoisomers. Configurations ofstereoisomers that owe their existence to hindered rotation about doublebonds are differentiated by their prefixes cis and trans (or Z and E),which indicate that the groups are on the same side (cis or Z) or onopposite sides (trans or E) of the double bond in the molecule accordingto the Cahn-Ingold-Prelog rules. All possible stereoisomers arecontemplated herein as individual stereoisomers or as a mixture ofstereoisomers.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which the presently described subject matter pertains.

Where a range of values is provided, for example, concentration ranges,percentage ranges, or ratio ranges, it is understood that eachintervening value, to the tenth of the unit of the lower limit, unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the described subject matter. Theupper and lower limits of these smaller ranges may independently beincluded in the smaller ranges, and such embodiments are alsoencompassed within the described subject matter, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either or both ofthose included limits are also included in the described subject matter.

Throughout the application, descriptions of various embodiments use“comprising” language. However, it will be understood by one of skill inthe art, that in some specific instances, an embodiment canalternatively be described using the language “consisting essentiallyof” or “consisting of”.

“Subject” as used herein refers to any animal classified as a mammal,including humans, domestic and farm animals, and zoo, sports, and petcompanion animals such as household pets and other domesticated animalssuch as, but not limited to, cattle, sheep, ferrets, swine, horses,poultry, rabbits, goats, dogs, cats and the like.

“Patient” as used herein refers to a subject in need of treatment of acondition, disorder, or disease, such as an acute or chronic airwaydisorder or disease.

For purposes of better understanding the present teachings and in no waylimiting the scope of the teachings, unless otherwise indicated, allnumbers expressing quantities, percentages or proportions, and othernumerical values used in the specification and claims, are to beunderstood as being modified in all instances by the term “about”.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the following specification and attached claims areapproximations that may vary depending upon the desired propertiessought to be obtained. At the very least, each numerical parametershould at least be construed in light of the number of reportedsignificant digits and by applying ordinary rounding techniques.

In one embodiment, the present subject matter relates to a compoundhaving the formula I:

or a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof, wherein: R₁ is hydrogen, C₁-C₆ alkyl, or C₃-C₆ cycloalkyl; R₂is hydrogen or a halogen; and R₃ is an aryl, heteroaryl, arylamine, orheteroarylamine, each of which may be optionally substituted with fromone to three substituents.

In one embodiment, the present subject matter relates to a compound offormula I, wherein R₁ is hydrogen or methyl.

In another embodiment, the present subject matter relates to a compoundof formula I, wherein R₂ is hydrogen or fluorine.

In a further embodiment, the present subject matter relates to acompound of formula I, wherein each substituent of the from one to threesubstituents for R₃ is independently selected from the group consistingof hydrogen, —COOH, —CH₂COOH, a trihaloalkoxy group, a trihaloalkylgroup, and an alkoxy group.

In yet another embodiment, the present subject matter relates to acompound of formula I, wherein each substituent of the from one to threesubstituents for R₃ is independently selected from the group consistingof hydrogen, —COOH, —CH₂COOH, a trifluoromethoxy group, atrifluoromethyl group, and a methoxy group.

In still another embodiment, the present subject matter relates to acompound of formula I, wherein R₃ is a phenyl, a pyrimidine, or apyridine, each of which may be optionally substituted with from one tothree substituents.

In still yet another embodiment, the present subject matter relates to acompound of formula I, wherein R₃ is an amino phenyl, an aminopyrimidine, or an amino pyridine, each of which phenyl, pyrimidine, andpyridine may be optionally substituted with from one to threesubstituents.

In an additional embodiment, the present subject matter relates to acompound of formula I, wherein R₃ is a phenyl, a pyrimidine, a pyridine,an amino phenyl, an amino pyrimidine, or an amino pyridine, each ofwhich phenyl, pyrimidine, and pyridine may be optionally substitutedwith from one to three substituents independently selected from thegroup consisting of hydrogen, —COOH, —CH₂COOH, a trihaloalkoxy group, atrihaloalkyl group, and an alkoxy group.

In an additional further embodiment, the present subject matter relatesto a compound of formula I, wherein R₃ is a phenyl, a pyrimidine, apyridine, an amino phenyl, an amino pyrimidine, or an amino pyridine,each of which phenyl, pyrimidine, and pyridine may be optionallysubstituted with from one to three substituents independently selectedfrom the group consisting of hydrogen, —COOH, —CH₂COOH, atrifluoromethoxy group, a trifluoromethyl group, and a methoxy group. Incertain embodiments in this regard, R₃ is selected from the groupconsisting of benzoic acid, acetic acid, 3-trifluoromethoxyphenyl,3-trifluoromethylphenyl, pyrimidin-5-yl, amino benzoic acid,3-trifluoromethoxyphenylamino, 3-methoxyphenylamino,3-trifluoromethylphenylamino, and pyridine-3-ylamino.

In another embodiment, the present subject matter relates to a compoundof formula I, wherein the compound is selected from the group consistingof 2-(3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)phenyl)ac etic acid(1); 3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)benzoic acid (2);3-fluoro-N-methyl-6-(3-(trifluoromethoxy)phenyl)-9H-carbazol-1-amine(3); 3-fluoro-N-methyl-6-(3-(trifluoromethyl)phenyl)-9H-carbazol-1-amine(4); 3-fluoro-N-methyl-6-(pyrimidin-5-yl)-9H-carbazol-1-amine (5);3-((6-fluoro-8-(methylamino)-9H-carbazol-3-yl)amino)benzoic acid (6);3-fluoro-N1-methyl-N6-(3-(trifluoromethoxy)phenyl)-9H-carbazole-1,6-diamine(7);3-fluoro-N1-methyl-N6-(3-(trifluoromethyl)phenyl)-9H-carbazole-1,6-diamine(8); 3-fluoro-N6-(3-methoxyphenyl)-N1-methyl-9H-carbazole-1,6-diamine(9); 3-fluoro-N1-methyl-N6-(pyridin-3-yl)-9H-carbazole-1,6-diamine (10);and a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof.

Said differently, the present subject matter can relate to compounds offormula I selected from the group consisting of:

and a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof.

It is to be understood that the present subject matter covers allcombinations of substituent groups referred to herein.

The present compounds may contain, e.g., when isolated in crystallineform, varying amounts of solvents. Accordingly, the present subjectmatter includes all solvates of the present compounds of formula I andpharmaceutically acceptable stereoisomers, esters, and/or salts thereof.Hydrates are one example of such solvates.

Further, the present subject matter includes all mixtures of possiblestereoisomers of the embodied compounds, independent of the ratio,including the racemates.

Salts of the present compounds, or the salts of the stereoisomersthereof, include all inorganic and organic acid addition salts and saltswith bases, especially all pharmaceutically acceptable inorganic andorganic acid addition salts and salts with bases, particularly allpharmaceutically acceptable inorganic and organic acid addition saltsand salts with bases customarily used in pharmacy.

Examples of acid addition salts include, but are not limited to,hydrochlorides, hydrobromides, phosphates, nitrates, sulfates, acetates,trifluoroacetates, citrates, D-gluconates, benzoates,2-(4-hydroxy-benzoyl)benzoates, butyrates, subsalicylates, maleates,laurates, malates, lactates, fumarates, succinates, oxalates, tartrates,stearates, benzenesulfonates (besilates), toluenesulfonates (tosilates),methanesulfonates (mesilates) and 3-hydroxy-2-naphthoates.

Examples of salts with bases include, but are not limited to, lithium,sodium, potassium, calcium, aluminum, magnesium, titanium, ammonium,meglumine and guanidinium salts. The salts include water-insoluble and,particularly, water-soluble salts.

The present compounds, the salts, the stereoisomers and the salts of thestereoisomers thereof may contain, e.g., when isolated in crystallineform, varying amounts of solvents. Included within the present scopeare, therefore, all solvates of the compounds of formula I, as well asthe solvates of the salts, the stereoisomers and the salts of thestereoisomers of the compounds of formula I.

The present compounds may be isolated and purified in a manner known perse, e.g., by distilling off the solvent in vacuo and recrystallizing theresidue obtained from a suitable solvent or subjecting it to one of thecustomary purification methods, such as column chromatography on asuitable support material.

Salts of the compounds of formula I and the stereoisomers thereof can beobtained by dissolving the free compound in a suitable solvent (by wayof non-limiting example, a ketone such as acetone, methylethylketone ormethylisobutylketone; an ether such as diethyl ether, tetrahydrofuraneor dioxane; a chlorinated hydrocarbon such as methylene chloride orchloroform; a low molecular weight aliphatic alcohol such as methanol,ethanol or isopropanol; a low molecular weight aliphatic ester such asethyl acetate or isopropyl acetate; or water) which contains the desiredacid or base, or to which the desired acid or base is then added. Theacid or base can be employed in salt preparation, depending on whether amono- or polybasic acid or base is concerned and depending on which saltis desired, in an equimolar quantitative ratio or one differingtherefrom. The salts are obtained by filtering, reprecipitating,precipitating with a non-solvent for the salt or by evaporating thesolvent. Salts obtained can be converted into the free compounds which,in turn, can be converted into salts. In this manner, pharmaceuticallyunacceptable salts, which can be obtained, for example, as processproducts in the manufacturing on an industrial scale, can be convertedinto pharmaceutically acceptable salts by processes known to the personskilled in the art.

Pure diastereomers and pure enantiomers of the present compounds can beobtained, e.g., by asymmetric synthesis, by using chiral startingcompounds in synthesis and by splitting up enantiomeric anddiastereomeric mixtures obtained in synthesis. Preferably, the purediastereomeric and pure enantiomeric compounds are obtained by usingchiral starting compounds in synthesis.

Enantiomeric and diastereomeric mixtures can be split up into the pureenantiomers and pure diastereomers by methods known to a person skilledin the art. Preferably, diastereomeric mixtures are separated bycrystallization, in particular fractional crystallization, orchromatography. Enantiomeric mixtures can be separated, e.g., by formingdiastereomers with a chiral auxiliary agent, resolving the diastereomersobtained and removing the chiral auxiliary agent. As chiral auxiliaryagents, for example, chiral acids can be used to separate enantiomericbases and chiral bases can be used to separate enantiomeric acids viaformation of diastereomeric salts. Furthermore, diastereomericderivatives such as diastereomeric esters can be formed fromenantiomeric mixtures of alcohols or enantiomeric mixtures of acids,respectively, using chiral acids or chiral alcohols, respectively, aschiral auxiliary agents. Additionally, diastereomeric complexes ordiastereomeric clathrates may be used for separating enantiomericmixtures. Alternatively, enantiomeric mixtures can be split up usingchiral separating columns in chromatography. Another suitable method forthe isolation of enantiomers is enzymatic separation.

In one embodiment, the present compounds can be prepared according tothe following reaction scheme:

Procedure A: Preparation of5-Bromo-1-(4-fluoro-2-nitrophenyl)-1H-benzotriazole II

To a suspension of 6-bromo-1-hydroxy-1H-benzotriazole (20 mmol) inCH₂Cl₂ (50 mL) was added pyridine (80 mmol), using 4 Å molecular sieves(750 mg), and the mixture was stirred until the solid dissolved. Next4-fluoro-2-nitrophenylboronic acid (23 mmol) and Cu(OAc)₂ (20 mmol) wereadded, and the mixture was stirred for 24 h at room temperature, underan atmosphere of oxygen gas. The mixture was evaporated under reducedpressure and purified by column chromatography to provide thecorresponding N-oxide benzotriazole. To a solution of the N-oxidebenzotriazole (15 mmol) in MeCN (15 mL) was added B₂(OH)₄ (17 mmol) andheated at 50° C. for 5 h. The solvent was removed under reduced pressureand the residue was purified by flash chromatography to afford theexpected product II. Elemental Analysis: Calculated C, 42.76; H, 1.79;N, 16.62; Found C, 42.68; H, 1.85; N, 16.57.

Procedure B: Preparation of 6-bromo-3-fluoro-1-nitro-9H-carbazole III

A suspension of benzotriazole II (10 mmol) in PPA (2 g) was stirred andheated to 220° C. for 10 min. After cooling, the reaction mixture wasdissolved in a small volume of water, made basic by adding ammoniumhydroxide, and cooled. The precipitate formed was filtered off, washedwith water and recrystallized to afford carbazole derivative III.Elemental Analysis: Calculated C, 46.63; H, 1.96; N, 9.06; Found C,46.71; H, 2.04; N, 8.98.

Procedure C: Preparation of6-bromo-3-fluoro-N-methyl-9H-carbazol-1-amine IV

To a suspension of nitro carbazole III (10 mmol) in ethanol (30 ml) andwater (10 ml), was added Na₂S₂O₄ (40 mmol) and heated at reflux for 5 h.After cooling to room temperature, concentrated hydrochloric acid (15ml) was added carefully to the reaction mixture, and heated at refluxfor 30 min. The precipitate formed was filtered off and washed with asmall amount of hot water. The filtrate was evaporated to about 30 ml,brought to pH=10 by adding ammonium hydroxide, and extracted withCH₂Cl₂. The combined organic layers were dried over MgSO₄, then filteredand the solvent was removed under reduced pressure to afford aminocarbazole which was heated at reflux with 10 mL of formic acid for 2 h.After cooling at room temperature, cold water was added and the obtainedprecipitate was filtered, washed with water and recrystallized toprovide the corresponding N-formyl carbazole. To a suspension of LiAlH₄(5 mmol) in 5 mL THF was added dropwise at 10° C. a solution of theN-formyl carbazole (5 mmol) in 10 mL THF. The reaction mixture wasstirred at room temperature for 18 h and then quenched with a 10% NaOHand extracted with dichloromethane. The combined organic layers weredried over MgSO₄, then filtered and the solvent was removed underreduced pressure. The product was purified by flash chromatography toafford the expected product IV. Elemental Analysis: Calculated C, 53.27;H, 3.44; N, 9.56; Found C, 53.33; H, 3.41; N, 9.62.

Procedure D: General preparation ofN-methyl-6-aryl-3-fluoro-9H-carbazol-1-amine Va

To a suspension of carbazole IV (1 mmol) in toluene (10 mL) were addedPd₂(dba)₃ (0.1 mmol), Xantphos (0.2 mmol) and Na₂CO₃ (3 mmol, 2 mL H2O2O) and arylboronic acid (1.5 mmol) and heated at reflux for 4 h underargon atmosphere, and then concentrated under reduced pressure. Thecrude product was dissolved in ethyl acetate (20 mL) and washed withbrine and water. The combined organic layers were dried over MgSO₄, thenfiltered and the solvent was removed under reduced pressure. The productwas purified by flash chromatography or by crystallization to afford theexpected product Va.

General preparation of N-methyl-6-arylamino-3-fluoro-9H-carbazol-1-amineVb

A sealed pressure tube with stir bar was charged with carbazole IV (0.5mmol), [Pd₂(dba)₃] (37 mg, 0.04 mmol), X-Phos (38 mg, 0.08 mmol), andK₂CO₃ (190 mg, 1.37 mmol). The tube was evacuated and back-filled withargon (repeated for three additional times). Degassed tBuOH (1 mL) andthe selected arylamine (0.65 mmol) were added and the reaction mixturewas stirred at 100° C. for 12 h. After cooling to room temperature, thesolution was quenched with H2O 2O and extracted with ethyl acetate. Thecombined organic layers were dried over MgSO₄, then filtered and thesolvent was removed under reduced pressure. The product was purified byflash chromatography or by crystallization to afford the expectedproduct Vb.

In another embodiment, the present subject matter is directed topharmaceutical compositions comprising a therapeutically effectiveamount of the compounds as described herein together with one or morepharmaceutically acceptable carriers, excipients, or vehicles. In someembodiments, the present compositions can be used for combinationtherapy, where other therapeutic and/or prophylactic ingredients can beincluded therein.

The present subject matter further relates to a pharmaceuticalcomposition, which comprises at least one of the present compoundstogether with at least one pharmaceutically acceptable auxiliary.

In an embodiment, the pharmaceutical composition comprises one or two ofthe present compounds, or one of the present compounds.

Non-limiting examples of suitable excipients, carriers, or vehiclesuseful herein include liquids such as water, saline, glycerol,polyethyleneglycol, hyaluronic acid, ethanol, and the like. Suitableexcipients for nonliquid formulations are also known to those of skillin the art. A thorough discussion of pharmaceutically acceptableexcipients and salts useful herein is available in Remington'sPharmaceutical Sciences, 18th Edition. Easton, Pa., Mack PublishingCompany, 1990, the entire contents of which are incorporated byreference herein.

The present compounds are typically administered at a therapeutically orpharmaceutically effective dosage, e.g., a dosage sufficient to providetreatment for an acute or chronic airway disease or disorder.Administration of the compounds or pharmaceutical compositions thereofcan be by any method that delivers the compounds systemically and/orlocally. These methods include oral routes, parenteral routes,intraduodenal routes, and the like.

While human dosage levels have yet to be optimized for the presentcompounds, generally, a daily dose is from about 0.01 to 10.0 mg/kg ofbody weight, for example about 0.1 to 5.0 mg/kg of body weight. Theprecise effective amount will vary from subject to subject and willdepend upon the species, age, the subject's size and health, the natureand extent of the condition being treated, recommendations of thetreating physician, and the therapeutics or combination of therapeuticsselected for administration. The subject may be administered as manydoses as is required to reduce and/or alleviate the signs, symptoms, orcauses of the disease or disorder in question, or bring about any otherdesired alteration of a biological system.

In employing the present compounds for treatment of a bacterialinfection, any pharmaceutically acceptable mode of administration can beused with other pharmaceutically acceptable excipients, including solid,semi-solid, liquid or aerosol dosage forms, such as, for example,tablets, capsules, powders, liquids, suspensions, suppositories,aerosols or the like. The present compounds can also be administered insustained or controlled release dosage forms, including depotinjections, osmotic pumps, pills, transdermal (includingelectrotransport) patches, and the like, for the prolongedadministration of the compound at a predetermined rate, preferably inunit dosage forms suitable for single administration of precise dosages.

The present compounds may also be administered as compositions preparedas foods for animals, including medical foods, functional food, specialnutrition foods and dietary supplements. A “medical food” is a productprescribed by a physician that is intended for the specific dietarymanagement of a disorder or health condition for which distinctivenutritional requirements exist and may include formulations fed througha feeding tube (referred to as enteral administration or gavageadministration).

A “dietary supplement” shall mean a product that is intended tosupplement the human diet and may be provided in the form of a pill,capsule, tablet, or like formulation. By way of non-limiting example, adietary supplement may include one or more of the following dietaryingredients: vitamins, minerals, herbs, botanicals, amino acids, anddietary substances intended to supplement the diet by increasing totaldietary intake, or a concentrate, metabolite, constituent, extract, orcombinations of these ingredients, not intended as a conventional foodor as the sole item of a meal or diet. Dietary supplements may also beincorporated into foodstuffs, such as functional foods designed topromote control of glucose levels. A “functional food” is an ordinaryfood that has one or more components or ingredients incorporated into itto give a specific medical or physiological benefit, other than a purelynutritional effect. “Special nutrition food” means ingredients designedfor a particular diet related to conditions or to support treatment ofnutritional deficiencies.

Generally, depending on the intended mode of administration, thepharmaceutically acceptable composition will contain about 0.1% to 90%,for example about 0.5% to 50%, by weight of a compound or salt of thepresent compounds, the remainder being suitable pharmaceuticalexcipients, carriers, etc.

One manner of administration for the conditions detailed above is oral,using a convenient daily dosage regimen which can be adjusted accordingto the degree of affliction. For such oral administration, apharmaceutically acceptable, non-toxic composition is formed by theincorporation of any of the normally employed excipients, such as, forexample, mannitol, lactose, starch, magnesium stearate, sodiumsaccharine, talcum, cellulose, sodium crosscarmellose, glucose, gelatin,sucrose, magnesium carbonate, and the like. Such compositions take theform of solutions, suspensions, tablets, dispersible tablets, pills,capsules, powders, sustained release formulations and the like.

The present compositions may take the form of a pill or tablet and thusthe composition may contain, along with the active ingredient, a diluentsuch as lactose, sucrose, dicalcium phosphate, or the like; a lubricantsuch as magnesium stearate or the like; and a binder such as starch, gumacacia, polyvinylpyrrolidine, gelatin, cellulose and derivativesthereof, and the like.

Liquid pharmaceutically administrable compositions can, for example, beprepared by dissolving, dispersing, etc. an active compound as definedabove and optional pharmaceutical adjuvants in a carrier, such as, forexample, water, saline, aqueous dextrose, glycerol, glycols, ethanol,and the like, to thereby form a solution or suspension. If desired, thepharmaceutical composition to be administered may also contain minoramounts of nontoxic auxiliary substances such as wetting agents,emulsifying agents, or solubilizing agents, pH buffering agents and thelike, for example, sodium acetate, sodium citrate, cyclodextrinederivatives, sorbitan monolaurate, triethanolamine acetate,triethanolamine oleate, etc.

For oral administration, a pharmaceutically acceptable non-toxiccomposition may be formed by the incorporation of any normally employedexcipients, such as, for example, pharmaceutical grades of mannitol,lactose, starch, magnesium stearate, talcum, cellulose derivatives,sodium crosscarmellose, glucose, sucrose, magnesium carbonate, sodiumsaccharin, talcum and the like. Such compositions take the form ofsolutions, suspensions, tablets, capsules, powders, sustained releaseformulations and the like.

For a solid dosage form, a solution or suspension in, for example,propylene carbonate, vegetable oils or triglycerides, may beencapsulated in a gelatin capsule. Such diester solutions, and thepreparation and encapsulation thereof, are disclosed in U.S. Pat. Nos.4,328,245; 4,409,239; and 4,410,545, the contents of each of which areincorporated herein by reference. For a liquid dosage form, thesolution, e.g., in a polyethylene glycol, may be diluted with asufficient quantity of a pharmaceutically acceptable liquid carrier,e.g., water, to be easily measured for administration.

Alternatively, liquid or semi-solid oral formulations may be prepared bydissolving or dispersing the active compound or salt in vegetable oils,glycols, triglycerides, propylene glycol esters (e.g., propylenecarbonate) and the like, and encapsulating these solutions orsuspensions in hard or soft gelatin capsule shells.

Other useful formulations include those set forth in U.S. Pat. Nos. Re.28,819 and 4,358,603, the contents of each of which are herebyincorporated by reference.

Another manner of administration is parenteral administration, generallycharacterized by injection, either subcutaneously, intramuscularly orintravenously. Injectables can be prepared in conventional forms, eitheras liquid solutions or suspensions, solid forms suitable for solution orsuspension in liquid prior to injection, or as emulsions. Suitableexcipients are, for example, water, saline, dextrose, glycerol, ethanolor the like. In addition, if desired, the pharmaceutical compositions tobe administered may also contain minor amounts of non-toxic auxiliarysubstances such as wetting or emulsifying agents, pH buffering agents,solubility enhancers, and the like, such as for example, sodium acetate,sorbitan monolaurate, triethanolamine oleate, cyclodextrins, etc.

Another approach for parenteral administration employs the implantationof a slow-release or sustained-release system, such that a constantlevel of dosage is maintained. The percentage of active compoundcontained in such parenteral compositions is highly dependent on thespecific nature thereof, as well as the activity of the compound and theneeds of the subject. However, percentages of active ingredient of 0.01%to 10% in solution are employable and will be higher if the compositionis a solid which will be subsequently diluted to the above percentages.The composition may comprise 0.2% to 2% of the active agent in solution.

Nasal solutions of the active compound alone or in combination withother pharmaceutically acceptable excipients can also be administered.

Formulations of the active compound or a salt may also be administeredto the respiratory tract as an aerosol or solution for a nebulizer, oras a microfine powder for insufflation, alone or in combination with aninert carrier such as lactose. In such a case, the particles of theformulation have diameters of less than 50 microns, for example lessthan 10 microns.

The present compounds have valuable pharmaceutical properties, whichmake them commercially utilizable. Accordingly, the present subjectmatter further relates to use of the present compounds for the treatmentof diseases or infections, especially bacterial infections and/ortuberculosis.

In this regard, the present subject matter relates to a method oftreating a bacterial infection in a patient, comprising administering toa patient in need thereof a therapeutically effective amount of acompound as described herein.

In a further embodiment, the bacterial infection treatable herein can becaused by Gram-positive Staphylococcus aureus, Staphylococcus aureusresistant to MRSA, epidermidis, Bacillus subtilis, Enterococcus faecium,Enterococcus faecium resistant to VRE, or Gram-negative organismsincluding Klebsiella pneumonia, Escherichia coli, or Pseudomonasaeruginosa, or any combination thereof.

In one specific embodiment, the bacterial infection can be caused byH37Rv type of M. tuberculosis strains. In another specific embodiment,the bacterial infection can be caused by E. coli.

The compounds as described herein are not only new but have veryvaluable antimicrobial properties. These compounds showed a broadspectrum of activity against gram positive and gram-negative bacteria,as well tuberculosis mycobacteria. They also showed potent activityagainst drug resistant bacteria such as MRSA and VRSA. The moleculartarget of these derivatives was identified as DNA Gyrase B. Anotherpotentially useful target herein is topoisomerase IV. Based on theirpharmacological profiles, the present compounds may find importantclinical applications for severe infectious diseases and tuberculosis

The present subject matter also relates to the use of a compound asdescribed herein in the manufacture of a pharmaceutical composition forthe treatment of bacterial infections, such as the diseases or disordersexemplified above. In particular, the present subject matter relates tothe use of a compound as described herein in the manufacture of apharmaceutical composition for the treatment or prophylaxis of bacterialinfection, such as, but not limited to, bacterial infections caused byGram-positive Staphylococcus aureus, Staphylococcus aureus resistant toMRSA, epidermidis, Bacillus subtilis, Enterococcus faecium, Enterococcusfaecium resistant to VRE, Gram-negative organisms including Klebsiellapneumonia, Escherichia coli, or Pseudomonas aeruginosa, H37Rv type of M.tuberculosis strains, E. coli, or any combination thereof.

The present subject matter further relates to a method of treating orpreventing a disease comprising administering to a patient in needthereof a therapeutically effective amount of at least one of thecompounds herein.

In particular, the present subject matter relates to a method oftreating one of the above-mentioned diseases or disorders comprisingadministering to a patient in need thereof a therapeutically effectiveamount of at least one of the compounds herein.

In an embodiment, the present subject matter relates to a method oftreating a bacterial infection caused by, for example, but not limitedto, Gram-positive Staphylococcus aureus, Staphylococcus aureus resistantto MRSA, epidermidis, Bacillus subtilis, Enterococcus faecium,Enterococcus faecium resistant to VRE, Gram-negative organisms includingKlebsiella pneumonia, Escherichia coli, or Pseudomonas aeruginosa, H37Rvtype of M. tuberculosis strains, E. coli, or any combination thereofcomprising administering to a patient in need thereof a therapeuticallyeffective amount of at least one of the compounds herein.

In the above methods, the patient is preferably a mammal, morepreferably a human. Furthermore, in the above methods, at least one ofthe present compounds can be used. In an embodiment, one or two of thepresent compounds are used, or one of the present compounds is used.

The following examples relate to various methods of manufacturingcertain specific compounds as described herein.

Example 1 2-(3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)phenyl)aceticacid (1)

Compound (1) was obtained in accordance with the general preparation ofN-methyl-6-aryl-3-fluoro-9H-carbazol-1-amine Va using2-(3-boronophenyl)acetic acid. Elemental Analysis: Calculated C, 72.40;H, 4.92; N, 8.04; Found C, 72.36; H, 4.87; N, 8.06.

Example 2 3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)benzoic acid (2)

Compound (2) was obtained in accordance with the general preparation ofN-methyl-6-aryl-3-fluoro-9H-carbazol-1-amine Va using3-carboxyphenylboronic acid. Elemental Analysis: Calculated C, 71.85; H,4.52; N, 8.38; Found C, 71.81; H, 4.49; N, 8.34.

Example 33-fluoro-N-methyl-6-(3-(trifluoromethoxy)phenyl)-9H-carbazol-1-amine (3)

Compound (3) was obtained in accordance with the general preparation ofN-methyl-6-aryl-3-fluoro-9H-carbazol-1-amine Va using3-trifluoromethoxyphenylboronic acid. Elemental Analysis: Calculated C,64.17; H, 3.77; N, 7.48; Found C, 64.20; H, 3.72; N, 7.44.

Example 43-fluoro-N-methyl-6-(3-(trifluoromethyl)phenyl)-9H-carbazol-1-amine (4)

Compound (4) was obtained in accordance with the general preparation ofN-methyl-6-aryl-3-fluoro-9H-carbazol-1-amine Va using3-trifluoromethylphenylboronic acid. Elemental Analysis: Calculated C,67.04; H, 3.94; N, 7.82; Found C, 67.09; H, 3.95; N, 7.89.

Example 5 3-fluoro-N-methyl-6-(pyrimidin-5-yl)-9H-carbazol-1-amine (5)

Compound (5) was obtained in accordance with the general preparation ofN-methyl-6-aryl-3-fluoro-9H-carbazol-1-amine Va usingpyrimidine-5-boronic acid. Elemental Analysis: Calculated C, 69.85; H,4.48; N, 19.17; Found C, 69.78; H, 4.53; N, 19.26.

Example 6 3-((6-fluoro-8-(methylamino)-9H-carbazol-3-yl)amino)benzoicacid (6)

Compound (6) was obtained in accordance with the general preparation ofN-methyl-6-arylamino-3-fluoro-9H-carbazol-1-amine Vb using3-aminobenzoic acid. Elemental Analysis: Calculated C, 68.76; H, 4.62;N, 12.03; Found C, 69.71; H, 4.58; N, 11.95.

Example 73-fluoro-N1-methyl-N6-(3-(trifluoromethoxy)phenyl)-9H-carbazole-1,6-diamine(7)

Compound (7) was obtained in accordance with the general preparation ofN-methyl-6-arylamino-3-fluoro-9H-carbazol-1-amine Vb using3-trifluoromethoxy aniline. Elemental Analysis: Calculated C, 61.70; H,3.88; N, 10.79; Found C, 61.78; H, 3.91; N, 10.85.

Example 83-fluoro-N1-methyl-N6-(3-(trifluoromethyl)phenyl)-9H-carbazole-1,6-diamine(8)

Compound (8) was obtained in accordance with the general preparation ofN-methyl-6-arylamino-3-fluoro-9H-carbazol-1-amine Vb using3-trifluoromethylaniline. Elemental Analysis: Calculated C, 64.34; H,4.05; N, 11.25; Found C, 64.39; H, 3.92; N, 11.22.

Example 93-fluoro-N6-(3-methoxyphenyl)-N1-methyl-9H-carbazole-1,6-diamine (9)

Compound (9) was obtained in accordance with the general preparation ofN-methyl-6-arylamino-3-fluoro-9H-carbazol-1-amine Vb using3-methoxyaniline. Elemental Analysis: Calculated C, 71.63; H, 5.41; N,12.53; Found C, 71.66; H, 5.33; N, 12.54.

Example 10 3-fluoro-N1-methyl-N6-(pyridin-3-yl)-9H-carbazole-1,6-diamine(10)

Compound (10) was obtained in accordance with the general preparation ofN-methyl-6-arylamino-3-fluoro-9H-carbazol-1-amine Vb using3-aminopyridine. Elemental Analysis: Calculated C, 70.57; H, 4.94; N,18.29; Found C, 70.49; H, 4.91; N, 18.21.

Example 11 Antibacterial Activity Evaluation

The following example relates to the antibacterial effectiveness ofcertain specific compounds as described herein.

Compounds 1-10 as identified above were evaluated for in vitroantibacterial activity according to the reported procedure (Methods forDilution Antimicrobial Susceptibility Tests for Bacteria That GrowAerobically; Approved Standard—Tenth Edition. CLSI document M07-A10.Wayne. PA: Clinical and Laboratory Standards Institute. 2015) againstbacterial strains comprising Gram-positive Staphylococcus aureus,Staphylococcus aureus resistant to MRSA, epidermidis, Bacillus subtilis,Enterococcus faecium, Enterococcus faecium resistant to VRE, andGram-negative organisms including Klebsiella pneumonia, Escherichiacoli, Pseudomonas aeruginosa.

The biological results obtained demonstrated that the present compoundspossess favorable antimicrobial activity. By way of non-limitingexample, the compound of Example 1 displayed promising antibacterialactivity against various drug sensitive and drug resistant bacterialstrains, as reported in Table 1.

TABLE 1 Antibacterial Activity of Compound 1 MIC μg/mL MicroorganismsCompound 6 Ciprofloxacin Vancomycin Staphylococcus aureus ATCC 0.75 0.51 29213 Staphylococcus aureus ATCC 1 16 1 BAA-1556 (MERSA resistant)Staphylococcus epidermidis 0.5 0.25 1 Bacillus subtilis MTCC 441 0.750.25 0.5 Enterococcus faecium ATCC 1 4 0.5 35667 Enterococcus faeciumATCC 2 16 >128 51559 (VRE resistant) Klebsiella pneumonia MTCC 618 10.75 >128 Escherichia coli MTCC 443 32 0.05 >128 Pseudomonas aeruginosaMTCC 16 0.75 >128 741

Example 12 Anti-tubercular Properties

The antitubercular property of the compounds 1-10 was evaluated towardsH37Rv type of M. tuberculosis strains. The inoculum was prepared fromfresh Lowenstein-Jensen re-suspended in 7H9-5 medium (7H9 broth, 0.5%glycerol, 0.1% casitone, supplemented with oleicacid/albumin/dextrose/catalase (OADC), adjusted to a McFarland tube No.1 and further diluted using sterile saline 1:20; 100 μL was used asinoculums. Each drug stock solution was thawed and diluted in 7H9-S atfourfold the final highest concentration assessed. Using one hundredmicroliter volume of 7H9-S broth, serial two-fold dilution was preparedof each drug directly in a sterile 96-well micro-titer plate. On eachmicroplate, a growth control that did not contain any antibiotic andcomposed of a sterile control were also effectuated. As water and mediacommonly evaporate from the closest wells to the plate perimeter duringculture, sterile water was added to the perimeters of the wells toprevent evaporation during the incubation. The plate was covered thensealed in a plastic bag and incubated at a temperature of 37° C. innormal atmosphere. After seven days of incubation, alamar blue solution(30 mL) was added to each well and the plate was re-incubated overnight.50 μL of alamar blue having 0.25 μM concentration were added. A changein color from blue (oxidized state) to pink (reduced) indicated thegrowth of bacteria and MIC was defined as the lowest concentration ofdrug that prevented this change in color.

The biological results demonstrated that the present compounds possessfavorable anti-mycobacterial activity. By way of example, the compoundof Example 1 displayed a promising anti-mycobacterial activity of 2μg/mL against Mycobacterium tuberculosis H37Rv strain.

Example 13 Evaluation of Inhibitory Activities on E. coli DNA Gyrase

Inhibitory potencies were investigated utilizing the Inspiralis assay onstreptavidin-coated 96-well microtiter plates. First, the plates wererehydrated with buffer (20 mM Tris-HCl with pH 7.6, 0.01% w/v BSA, 0.05%v/v Tween 20, 137 mM NaCl) and the biotinylated oligonucleotide was thenimmobilized. After washing off the unbound oligonucleotide, the enzymetest was performed. The reaction volume of 30 μL in buffer (35 mMTris×HCl with pH 7.5, 4 mM MgCl2, 24 mM KCl, 2 mM DTT, 1.8 mMspermidine, 1 mM ATP, 6.5% w/v glycerol, 0.1 mg/mL albumin) contained1.5 U of DNA gyrase from E. coli, 0.75 μg of relaxed pNO1 plasmid, and 3μL solution of the inhibitor in 10% DMSO and 0.008% Tween 20. Reactionsolutions were incubated at 37° C. for 30 min. After that, the TF buffer(50 mM NaOAc with pH 5.0, 50 mM NaCl and 50 mM MgCl₂) was added toterminate the enzymatic reaction. After additional incubation for 30 minat rt, during which biotinoligonucleotide-plasmid triplex was formed,the unbound plasmid was washed off using TF buffer and SybrGOLD in T10buffer (10 mM Tris HCl with pH 8.0 and 1 mM EDTA) was added. Thefluorescence was measured with a microplate reader (BioTek Synergy H4,excitation: 485 nm, emission: 535 nm). Initial screening was done at 100or 10 μM concentration of inhibitors. For the most active inhibitors,IC50 was determined using seven concentrations of the tested compounds.GraphPad Prism software was used to calculate the IC50 values. Theresult is given as the average value of three independent measurements.Novobiocin was used as a positive control.

The biological results demonstrated that the present compounds possessedfavorable DNA Gyrase activity. By way of example, the compound ofExample 1 displayed promising E. coli DNA Gyrase of 80 nM. In the sameexperimental condition, the reference control Novabiocin inhibited E.coli DNA Gyrase activity of 150 nM.

It is to be understood that the aminocarbazole compounds asantibacterial agents are not limited to the specific embodimentsdescribed above, but encompasses any and all embodiments within thescope of the generic language of the following claims enabled by theembodiments described herein, or otherwise shown in the drawings ordescribed above in terms sufficient to enable one of ordinary skill inthe art to make and use the claimed subject matter.

We claim:
 1. A compound having the formula I:

or a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof, wherein: R₁ is hydrogen, C₁-C₆ alkyl, or C₃-C₆ cycloalkyl; R₂is hydrogen or a halogen; and R₃ is an aryl, heteroaryl, arylamine, orheteroarylamine, each of which may be optionally substituted with fromone to three substituents, and wherein each of the from one to threesubstituents is independently selected from the group consisting ofhydrogen, —COOH, —CH₂COOH, a trihaloalkoxy group, a trihaloalkyl group,and an alkoxy group.
 2. The compound as recited in claim 1, wherein R₁is hydrogen or methyl.
 3. The compound as recited in claim 1, wherein R₂is hydrogen or fluorine.
 4. The compound as recited in claim 1, whereineach substituent of the from one to three substituents for R₃ isindependently selected from the group consisting of hydrogen, —COOH,—CH₂COOH, a trifluoromethoxy group, a trifluoromethyl group, and amethoxy group.
 5. The compound as recited in claim 1, wherein R₃ is aphenyl, a pyrimidine, or a pyridine, each of which may be optionallysubstituted with from one to three substituents.
 6. The compound asrecited in claim 1, wherein R₃ is an amino phenyl, an amino pyrimidine,or an amino pyridine, each of which phenyl, pyrimidine, and pyridine maybe optionally substituted with from one to three substituents.
 7. Thecompound as recited in claim 1, wherein R₃ is a phenyl, a pyrimidine, apyridine, an amino phenyl, an amino pyrimidine, or an amino pyridine,each of which phenyl, pyrimidine, and pyridine may be optionallysubstituted with ho from one to three substituents, and wherein each ofthe from one to three substituents is independently selected from thegroup consisting of hydrogen, —COOH, —CH₂COOH, a trihaloalkoxy group, atrihaloalkyl group, and an alkoxy group.
 8. The compound as recited inclaim 1, wherein the compound is selected from the group consisting of:2-(3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)phenyl)acetic acid (1);3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)benzoic acid (2);3-fluoro-N-methyl-6-(3-(trifluoromethoxy)phenyl)-9H-carbazol-1-amine(3); 3-fluoro-N-methyl-6-(3-(trifluoromethyl)phenyl)-9H-carbazol-1-amine(4); 3-fluoro-N-methyl-6-(pyrimidin-5-yl)-9H-carbazol-1-amine (5);3-((6-fluoro-8-(methylamino)-9H-carbazol-3-yl)amino)benzoic acid (6);3-fluoro-N1-methyl-N6-(3-(trifluoromethoxy)phenyl)-9H-carbazole-1,6-diamine(7);3-fluoro-N1-methyl-N6-(3-(trifluoromethyl)phenyl)-9H-carbazole-1,6-diamine(8); 3-fluoro-N6-(3-methoxyphenyl)-N1-methyl-9H-carbazole-1,6-diamine(9); 3-fluoro-N1-methyl-N6-(pyridin-3-yl)-9H-carbazole-1,6-diamine (10);and a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof.
 9. A pharmaceutical composition comprising a therapeuticallyeffective amount of the compound of claim 1 and a pharmaceuticallyacceptable carrier.
 10. A method of treating a bacterial infection in apatient, comprising administering to a patient in need thereof atherapeutically effective amount of the compound of claim
 1. 11. Themethod of claim 10, wherein the bacterial infection is caused byGram-positive Staphylococcus aureus, Staphylococcus aureus resistant toMRSA, epidermidis, Bacillus subtilis, Enterococcus faecium, Enterococcusfaecium resistant to VRE, or Gram-negative organisms includingKlebsiella pneumonia, Escherichia coli, or Pseudomonas aeruginosa. 12.The method of claim 10, wherein the bacterial infection is caused byH37Rv type of M. tuberculosis strains.
 13. The method of claim 11,wherein the bacterial infection is caused by E. coli.
 14. A compoundhaving the formula I:

or a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof, wherein R₁ is hydrogen or methyl; R₂ is hydrogen or fluorine;and R₃ is a phenyl, a pyrimidine, a pyridine, an amino phenyl, an aminopyrimidine, or an amino pyridine, each of which phenyl, pyrimidine, andpyridine may be optionally substituted with from one to threesubstituents independently selected from the group consisting ofhydrogen, —COOH, —CH₂COOH, a trihaloalkoxy group, a trihaloalkyl group,and an alkoxy group.
 15. A pharmaceutical composition comprising atherapeutically effective amount of the compound of claim 14 and apharmaceutically acceptable carrier.
 16. A method of treating abacterial infection in a patient, comprising administering to a patientin need thereof a therapeutically effective amount of the compound ofclaim
 14. 17. A compound selected from the group consisting of:2-(3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)phenyl)acetic acid (1);3-(6-fluoro-8-(methylamino)-9H-carbazol-3-yl)benzoic acid (2);3-fluoro-N-methyl-6-(3-(trifluoromethoxy)phenyl)-9H-carbazol-1-amine(3); 3-fluoro-N-methyl-6-(3-(trifluoromethyl)phenyl)-9H-carbazol-1-amine(4); 3-fluoro-N-methyl-6-(pyrimidin-5-yl)-9H-carbazol-1-amine (5);3-((6-fluoro-8-(methylamino)-9H-carbazol-3-yl)amino)benzoic acid (6);3-fluoro-N1-methyl-N6-(3-(trifluoromethoxy)phenyl)-9H-carbazole-1,6-diamine(7);3-fluoro-N1-methyl-N6-(3-(trifluoromethyl)phenyl)-9H-carbazole-1,6-diamine(8); 3-fluoro-N6-(3-methoxyphenyl)-N1-methyl-9H-carbazole-1,6-diamine(9); 3-fluoro-N1-methyl-N6-(pyridin-3-yl)-9H-carbazole-1,6-diamine (10);and a pharmaceutically acceptable salt, ester, stereoisomer, or solvatethereof.
 18. A pharmaceutical composition comprising a therapeuticallyeffective amount of the compound of claim 17 and a pharmaceuticallyacceptable carrier.
 19. A method of treating a bacterial infection in apatient, comprising administering to a patient in need thereof atherapeutically effective amount of the compound of claim 17.